Device for driving a wiper arm

ABSTRACT

The invention is based on a device for driving a wiper arm, having a lever mechanism ( 10 ) which has a drive lever ( 14 ), pivotable about a drive axis ( 12 ), and a drop arm ( 18 ) pivotable about an axis ( 16 ), wherein the drive lever ( 14 ) and the drop arm ( 18 ) are connected to one another via hinges ( 22, 24 ) by means of a coupling rod ( 20 ), which carries a fastening part ( 34 ) of the wiper arm. 
     It is proposed that the fastening part ( 34 ) is separably fastened to the coupling rod ( 20 ) and can be adjusted relative to the coupling rod ( 20 ) about a displacement axis ( 38 ), extending in the longitudinal direction, in a displacement region ( 40 ).

PRIOR ART

The invention is based on a device for driving a wiper arm asgenerically defined by the preamble to claim 1.

Wiper systems with a plurality of windshield wipers for motor vehiclesare fastened with their wiper bearings to the vehicle body directly orindirectly via a mounting plate. The mounting plate or a tubularmounting plate—if the wiper carrier also has tubular hollowprofiles—includes a motor mounting plate, which has a wiper drivemechanism with a wiper motor and a gear mounted on it. A power takeoffshaft of the gear is supported in a gear dome and, as a rule via a crankand connecting rods, drives further cranks, which are connected solidlyto one drive shaft for each windshield wiper.

It is also possible for the drive shaft of the wiper motor to drive afour-bar lever mechanism. The four-bar lever mechanism has a drivelever, which is seated pivotably on a drive axis and is connectedpivotably via a coupling rod to a drop arm. The drop arm is seatedpivotably on a stationary shaft. A fastening part of a wiper arm isintegrally formed onto the coupling rod and together with it forms aso-called four-bar wiper lever, to which the hinge part of the wiper armis fastened via a foldaway hinge. The drive lever can be driven directlyby a power takeoff shaft of the wiper motor or via a crank andconnecting rods. It can also be embodied as a cross lever. Thekinematics of the four-bar lever mechanism produce a combinedreciprocating and swiveling motion of the windshield wiper. As a result,the windshield wiper is better able to follow the angular contour of avehicle window.

A wiper blade with a support bracket system and a wiper strip ispivotably connected to the wiper arm. For a good outcome of wiping andto avoid chattering, it is important that the wiper strip with its wiperlip be guided over the vehicle window at a certain approach angle.Although the production tolerances of the individual, numerouscomponents of the windshield wiper and its drive mechanism are onlyslight, still the sum of the tolerances, together with those of thefastening to the vehicle body and of the vehicle body itself, is sogreat that an optimal approach angle is not assured in mass production.While the wiper systems, because of their high ratio of length to width,are well oriented crosswise to the vehicle direction, poor orientationresults above all in the longitudinal direction of the vehicle.

ADVANTAGES OF THE INVENTION

According to the invention, the fastening part is separably fastened tothe coupling rod and can be adjusted relative to the coupling rod abouta displacement axis, extending in the longitudinal direction, in adisplacement region. As a result, the fastening part and with it thewiper arm with its wiper blade can be adjusted about its longitudinalaxis, so that the wiper strip during assembly is given its optimalapproach angle to the windshield, regardless of production tolerances ofthe vehicle.

The coupling rod is expediently screwed to the fastening part betweenthe hinges and, in the axial direction on both sides of the fasteningposition, has guide faces, on which the fastening part rests. As aresult, the bending forces that are transmitted from the wiper blade tothe fastening part are favorably absorbed by the coupling part. To keepthe pressure per unit of surface area between the guide faces andsupport faces low, it is advantageous that numerous guide faces, whichproduce a wide support spacing in the longitudinal direction, areprovided. Expediently, the guide faces are distributed circumferentiallyto the displacement axis over a region of more than 180°, so that theycan absorb bending forces in all directions. For that purpose, guidefaces that are located on the side walls of the coupling part can beutilized.

To make the fastening part pivotable about a longitudinal axis, theguide faces comprise parts of the jacket faces of bodies generated byrotation that are coaxial with the displacement axis, and thedisplacement axis expediently extends inside the coupling rod. Since theapproach angle of the wiper strip is meant to be changed by thedisplacement, it is advantageous if the displacement axis extends asparallel as possible to an associated wiper blade. The vertical positionof the wiper arm, and in particular the vertical position of thefastening part, in the region of the foldaway hinge, to the windshieldshould not vary, or should vary only slightly. This is achieved byproviding that the displacement axis intersects the hinge axis of thefoldaway hinge, or has the slightest possible spacing from the hingeaxis.

The fastening part expediently surrounds the coupling rod with aU-shaped profile open toward the coupling rod and is connected to thecoupling rod between the hinges, at the transverse wall of the U-shapedprofile. The U-shaped profile is resistant to bending and allows a widevariety of variation, so that guide faces can be disposed over a largearea between the coupling part and the fastening part. In the region ofthe fastening position, the transverse wall of the U-shaped profile ofthe fastening part has a bulge toward the open side of the U shapedprofile, and this bulge engages a corresponding indentation of thecoupling rod. The opposed walls of the bulge and indentation aredesigned such that they allow a displacement. They can also be calledguide faces.

Fastening elements in the form of screws, screw nuts, threaded bolts andthreaded stubs find space in the bulge without protruding past the outercontour of the fastening part. As a result, in a further feature of theinvention, a cap, preferably of plastic, can cover the fasteningposition by being slipped onto the coupling rod. This averts the riskthat in the motion of the coupling rod, parts will become caught betweenit and the levers pivotably connected to it. For reasons of appearanceand streamlining, it is expedient that the fastening part, in the regionof the connection point of the cap, has a step which is approximatelyequivalent to the thickness of the material of the cap, so that theouter contour of the cap adjoins the outer contour of the fastening partflush with it.

The adjustment serves the purpose above all of correcting for productiontolerances. To prevent the fastening part from being roughly assembledwrong or shifting arbitrarily if the screw fastening should come loose,it is expedient that the displacement region is limited, for instance toan angular range of less than 5°, and preferably to 3°. This purpose isserved by stops between the fastening part and the coupling rod, orbetween the elements that are solidly connected to these parts.

To enable an infinitely graduated displacement, the guide faces aresmooth, or for better frictional engagement are roughened. By means of afluting in the longitudinal direction parallel to the displacement axis,an incremental displaceability is attained. This is advantageous so thatthe adjustment from an outset position can be done in defined angularincrements.

DRAWING

Further advantages will become apparent from the ensuing description ofthe drawings. In the drawing, exemplary embodiments of the. inventionare shown. The drawing, specification and claims include numerouscharacteristics in combination. One skilled in the art will expedientlyconsider the characteristics individually as well and put them togetherto make useful further combinations.

Shown are:

FIG. 1, a detail of a lever mechanism;

FIG. 2, a lever mechanism of FIG. 1 with a fastening part;

FIG. 3, a perspective view of a coupling rod;

FIG. 4, a variant of FIG. 3;

FIG. 5, a longitudinal section through a coupling rod with a fasteningpart and a cover cap;

FIG. 6, a section taken along the VI—VI in FIG. 5;

FIG. 7, a section taken along the VII—VII in FIG. 5;

FIGS. 8-11, Variants of FIG. 7; and

FIG. 12, a section taken along the XII—XII in FIG. 5.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

The lever mechanism 10 shown in FIG. 1 includes a drive lever 14, whichis supported rotatably about a drive axis 12; a drop arm 18, which issupported rotatably about an axis 16; and a coupling rod 20, which isconnected via hinges 22, 24 to the drive lever 14 on one end and to thedrop arm 18 on the other end. The drive axis 12 and the axis 16 aredisposed on a vehicle body, not shown further, directly or indirectlyvia a mounting plate. The hinges 22, 24 are formed by hinge pins 54, 56,which are supported in the coupling rod 20 via bearing shells 58, 60(FIGS. 5, 6) and are riveted to the drop arm 18 and the drive lever 14,respectively.

A fastening position 94 for a fastening part 34 is located between thehinges 22 and 24. The fastening part has a U-shaped profile, open towardthe coupling rod 20, with which it surrounds the coupling rod 20 onthree sides. In the region of the fastening position 94, the couplingrod 20 has an indentation 44 on the upper side, and a bulge 42 of thetransverse wall 82 of the fastening part 34 engages this indentation.The fastening part 34 is fastened to the coupling rod 20 by at least onescrew connection. In the versions of FIG. 1, FIG. 2, FIG. 5, FIG. 7 andFIG. 8, the screw connection is formed by a threaded hole 32 in thecoupling rod 20 and by a screw 52, whose screw head 88 rests directly ona curved face of the fastening part 34 or indirectly on the fasteningpart 34 via a formed disk 66 (FIG. 8) and presses the fastening part 34against the coupling rod 20. It is also possible for a plurality ofscrew connections to be provided, preferably one after the other in thedirection of the displacement axis 38.

In the axial direction of the coupling rod 20, there are guide faces 26,28 on both sides of the screw connection 32, 52, and the fastening part34 is braced on these guide faces. The guide faces 26, 28 are formed bypartial faces of bodies generated by rotation that are located coaxiallyto a displacement axis 38, so that the fastening part 34 can be rotatedabout the displacement axis 38 and calibrated. The displacement axis 38extends substantially in the longitudinal direction of the fasteningpart 34 and thus parallel to a wiper blade, which is not further shownbut has a wiper strip and is pivotably connected to the fastening part34 via a wiper bearing and a hinge part by means of a foldaway hinge. Ahinge axis of the foldaway hinge is identified by reference numeral 36(FIG. 2).

In order for the bending forces that the wiper blade transmits to thefastening part 34 to be carried favorably onto the coupling rod 20, theguide faces 26, 28 have a suitably great axial spacing and asufficiently large contact area, so that the pressure per unit ofsurface area resulting from the bending forces is slight, compared tothe pressure per unit of surface area resulting from the locking forces.The guidance and retention of the fastening part 34 can be improved byfurther guide faces 30 on the sides of the coupling rod 20, whichfurther guide faces have a considerable axial length and thus form awide support spacing 78. The guide faces 26, 28, 30 are expedientlydisposed about the displacement axis 38 in such a way that theyencompass a region 80 of more than 180° (FIG. 7). As a result, evenforces exerted from below can be braced via guide faces 26, 38, 30 onthe coupling rod 20.

To enable infinitely variable adjustment of the fastening part 34, theguide faces 26, 28, 30 are smooth, or for better force transmission areroughened (FIG. 3). A version shown in FIG. 4 has guide faces 46, 48,which are fluted parallel to the displacement axis 38. As a result,beginning at a given position, it is possible to make the adjustment insmall, predetermined angular increments. The adjustment of the fasteningpart 34 serves to optimize the approach angle of the wiper strip to thewindshield. For this purpose, a relatively small displacement region 40,which amounts to less than 5°, preferably being 3°, suffices. Thedisplacement region 40 is limited by stops 64, which are disposedbetween the fastening part 34 and the coupling rod 20, or between partsthat are connected to them, for instance between a through hole 62 and athreaded bolt 68, or between a formed disk 66 and the fastening part 34,or other suitable parts of the fastening part 34 and the coupling rod20.

The screw connection between the fastening part 34 and the coupling rod20 can be embodied in various ways. FIG. 9 shows a threaded bolt 68 thatis integrally cast or press-fitted into the coupling rod 20 and ontowhich a screw nut 70 is screwed, which via a formed disk 66 presses thefastening part 34 against the guide faces 26, 28, 30, 46, 48. Theversion of FIG. 10 differs from this in that instead of the threadedbolt 68, a threaded stub 72, onto which the screw nut 70 is screwed, isintegrally formed onto a coupling rod 20 made as a deep-drawnsheet-metal part. Finally, FIG. 11 shows a variant in which the couplingrod 20 has a spherical recess 84, into which a threaded bolt 76 isinserted with a ball head 74; the threaded bolt 76 is screwed into athreaded stub 90 of the fastening part 34. This purpose is served by ahexagonal socket 86 on a face end of the threaded bolt 76.

The screw connections shown are located inside the bulge 42 of thefastening part 34, so that they do not protrude past the outer contourof the fastening part 34. They are expediently covered with a cap 50,which is slipped onto the coupling rod 20 (FIG. 5) and extends past thefastening position 94 into the region of the hinges 22, 24. This lessensthe risk of anything becoming caught in wiper operation within the rangeof motion of the coupling rod 20 and the drop arm 18 or the drive lever14. This prevents injuries and damage. The fastening part 34, in anattachment region 92, has a step which is adjoined flush on the outsideby the contour of the cap 50.

List of Reference Numerals

10 Lever mechanism

12 Drive axis

14 Drive lever

16 Axis

18 Drop arm

20 Coupling rod

22 Hinge

24 Hinge

26 Guide face

28 Guide face

30 Guide face

32 Threaded hole

34 Fastening part

36 Hinge axis

38 Displacement axis

40 Displacement region

42 Bulge

44 Indentation

46 Guide face

48 Guide face

50 Cap

52 Screw

54 Threaded bolt

56 Threaded bolt

58 Bearing shell

60 Bearing shell

62 Through hole

64 Stop

66 Formed disk

68 Threaded bolt

70 Screw nut

72 Threaded stub

74 Ball head

76 Threaded bolt

78 Support spacing

80 Region

82 Transverse wall

84 Recess

86 Hexagonal socket

88 Screw head

90 Threaded stub

92 Attachment region

94 Fastening position

What is claimed is:
 1. A device for driving a wiper arm, having a levermechanism (10) which has a drive lever (14), pivotable about a driveaxis (12), and a drop arm (18) pivotable about an axis (16), wherein thedrive lever (14) and the drop arm (18) are connected to one another viahinges (22, 24) by means of a coupling rod (20), which carries afastening part (34) of the wiper arm, characterized in that thefastening part (34) is separably fastened to the coupling rod (20) andcan be adjusted relative to the coupling rod (20) about a displacementaxis (38), extending in the longitudinal direction, in a displacementregion (40).
 2. The device of claim 1, characterized in that thecoupling rod (20) is screwed to the fastening part (34) between thehinges (22, 24) and, in the axial direction on both sides of thefastening position (94), has guide faces (26, 28, 30, 46, 48), on whichthe fastening part (34) rests, and the guide faces (26, 28, 30, 46, 48)comprise parts of the jacket faces of bodies generated by rotation thatare coaxial with the displacement axis (38), and the displacement axis(38) extends inside the coupling rod (20).
 3. The device of claim 1,characterized in that the displacement axis (38) extends as parallel aspossible to an associated wiper blade.
 4. The device of claim 1,characterized in that the displacement axis (38) extends at theslightest possible spacing from a hinge axis (36) of a foldaway hinge.5. The device of claim 1, characterized in that the fastening part (34)is fastened to the coupling rod (20) by a screw connection (32, 52; 68,72 and 70), and a formed disk (66) is provided between a screw head (88)or a screw nut (70) and the fastening part (34).
 6. The device of claim1, characterized in that the guide faces (26, 28, 30, 46, 48) have awide support spacing (78) in the longitudinal direction of the couplingrod (20), and in the circumferential direction relative to thedisplacement axis (38), they encompass a region (80) of more than 180°.7. The device of claim 1, characterized in that the fastening part (34)surrounds the coupling rod (20) with a U-shaped profile open toward thecoupling rod (20) and is connected to the coupling rod (20) between thehinges (22, 24), at the transverse wall (82) of the U-shaped profile. 8.The device of claim 7, characterized in that the transverse wall (82) ofthe fastening part (34) has a bulge (42) in the region of the fasteningposition (94) toward the open side of the U-shaped profile, which bulgeengages a corresponding indentation (44) in the coupling rod (20). 9.The device of claim 8, characterized in that at least one guide face(26, 28, 46, 48) is provided in the longitudinal direction in thevicinity of the bulge (42) or indentation (44).
 10. The device of claim1, characterized in that the guide faces (26, 28, 46, 48) are roughenedor are fluted in the longitudinal direction.
 11. The device of claim 1,characterized in that the coupling rod (20) has at least one integrallycast or press-fitted threaded bolt (68).
 12. The device of claim 1,characterized in that the coupling rod (20) is a deep-drawn sheet-metalpart with at least one integrally formed-on threaded stub (72).
 13. Thedevice of claim 1, characterized in that the coupling rod (20) has aspherical recess (84) with an opening for receiving a threaded bolt (76)with a ball head (74) and a hexagonal socket (86), and the threaded bolt(76) is screwed into a threaded stub (90) of the fastening part (34).14. The device of claim 1, characterized in that at least one stop (64)limits the displacement region (40).
 15. The device of claim 14,characterized in that the screw head (88), the formed disk (66), or athrough hole (62) for the screw (52), the threaded bolt (68) or thethreaded stub (72) forms the stop (64).
 16. The device of claim 14,characterized in that the displacement region (40) is less than 5°, andis preferably 3°.
 17. The device of claim 1, characterized in that thecoupling rod (20) has a cap (50), which covers the fastening position(94) between the coupling rod (20) and the fastening part (34) and/orthe adjoining region of the hinges (22, 24).
 18. The device of claim 17,characterized in that the fastening part (34), in the attachment region(92), has a step, which is adjoined flush on the outside by the contourof the cap (50).